This is just my personal opinion after around 20 years of global travel. It seems as though most people tend to flock to beach destinations for any sort of travel and while I do not begrudge anyone for doing that I'm of the mindset that I have seen enough of this sort of thing and actually kind of avoid going to such areas these days. There are many reasons why this is the case for me but here are the major ones.
Once you've seen a couple, you've seen them all
The beach is a lovely place, there is no denying that. I will never forget the first time I opted out of the traditional "beach week" that was customary for high school graduates in my city where they all went to a place nearby to get hammered drunk and just hang around at an area that was a couple hours from where we went to school without their parents. Instead, I decided to fly to the Bahamas with just one of my friends and his parents. When I saw that aquamarine water I was blown away. Years later I would travel to South East Asia and experience the same phenomenon. I have been to crystal-clear beaches in many different countries all around the world to the point where it doesn't really impress me anymore.
Once you've looked at it, gone for a paddle and depending on what coast you are on see a sunrise or sunset a few times, what else is there really to do? There isn't but so many things that can be done in this water and after a while you end up just hanging in the shade, drinking, and wondering what the hell you are doing there.
These are ALWAYS the most expensive places
The global phenomenon of everyone desiring to go to the beaches around the world keep the prices high at all of these locations. Even in areas where there isn't anything particularly beautiful about the ocean carries a big price with it. I'll use the Hamptons as an example
I wasn't expecting Caribbean style water when I visited a relative here but when we went out to the beach I kept my opinions to myself but the entire time I was thinking to myself "this is what people pay millions of dollars to be near?" It just doesn't do it for me.
Even when you go to backpacking locations in Mexico and Central America the beach areas, while very affordable in comparison to USA beach locations, they are still a lot more expensive than the rest of these countries and once again, once you have exhausted your wave riding options or just paddling in the water, now what? Ok, back to drinking in the shade!
Inland has much better nature, more exploration, and better values
This is true in nearly any place that I have ever visited that wasn't a land-locked country. The areas that are further from the beaches tend to be where the national parks are or just the better mountainous areas that you can explore often for free. Let's think about The Highlands in Malaysia for example or Khao Sok National Park in Thailand. Both of these places are ages from the beach. These enormous spots have so much natural beauty and wildlife that you could spend a month or more an either of them and be doings something different every day.
src Oh, and they have water you can swim in there as well
Hiking, photography, spelunking, swimming in waterfalls.... all of these things for the most part don't exist at really any beaches I have been to around the world. This also falls into category 2 of what I have written here in that even if it is a famous natural area, the lodging tends to be dramatically cheaper than if you are staying a few blocks from the beach.
The hassle factor
Tourist beach areas tend to have the most touts of any place in any country. This is because of the obvious: More tourists are there.
I've been to beaches around the world and one thing is true at almost all of them especially in developing countries. You are going to be hassled constantly to be buying something. Some of these people are relentless and are quite difficult to make them go away. Then, when you finally do succeed in getting them to move on, moments later they are replaced by someone doing exactly the same thing.
In one particularly odd and annoying beach in the Dominican Republic, there were people selling things IN THE WATER as if you actually were carrying money with you in the sea.
Of all the inland places I have been to, this annoyance is almost non-existent
I'm not trying to tell anyone that they are "wrong" for wanting to go to the beach but for me, someone who has spent decades traveling, I actually seek out places that are not at the beach for all the reasons I have listed above and many more. I think that most people when looking at a trip abroad only look at the coasts and I think this is a big mistake that will cause them to miss a great deal of what makes a particularly country unique because beaches, well, they are basically the same all around the world.